1. Field of the Invention
The present invention relates to electronic equipment, such as on-board automotive audio equipment, in which a control unit is detachably positioned on the main body of the equipment, and more particularly, to a locking and retaining mechanism for an electronic device with a detachable control unit.
2. Description of the Prior Art
Electronic audio equipment typically includes a control unit on which various push buttons and controls are provided. However, in some devices, a control unit for controlling the main body of the equipment is detachable from the equipment body.
FIG. 6 is a partial plan view showing a control unit and an equipment body for an on-board automotive audio device and is an example of the type of device discussed above. FIG. 7 is an enlarged plan view of a portion VII in FIG. 6.
In FIG. 6, an equipment body 1 includes a metal chassis 2, which is typically embedded in the dashboard of a vehicle, and a nose portion 3 which is a decorative portion typically made of resin (plastic) and mounted in front of the chassis 2. When the chassis 2 is embedded in the vehicle dashboard, the nose portion 3 is positioned almost corresponding to the front of the dashboard. A recessed portion 3a is formed on the front of the nose portion 3 and a control unit 4 is detachably attached in the recessed portion 3a.
The control unit 4 has an operating surface 4a which includes various control buttons 5 and possibly a liquid crystal display panel or other display. The control unit 4 and the front of the nose portion 3 are electrically connected to each other through an extractable connector (not shown). When the control unit 4 is detached from the equipment body 1 and carried away by the driver, the internal mechanisms and circuitry of the equipment body 1 remaining in the vehicle are inoperable. Thus, this configuration discourages the theft of equipment body 1 from the vehicle.
The attachment structure of the control unit 4 and the nose portion 3 are as follows. At the right end of FIG. 6, a projection 3b formed on the nose portion 3 and a recess 4b formed on the control unit 4 are engaged with each other. At the left end of FIG. 6, the control unit 4 has a lock groove 4c as shown in FIG. 7. A locking hook 6 is supported pivotally about a shaft 7 in the nose portion 3, and is urged counterclockwise by a spring 8. A lock release button 9 is mounted in a left edge portion 3c of the nose portion 3.
In order to attach the control unit 4, the recess 4b (see FIG. 6) is first engaged with the projection 3b, and the control unit 4 is pivoted about the engaging portion in a direction .alpha. so as to be fitted in the recessed portion 3a of the nose portion 3. At this time, the lock groove 4c formed on the control unit 4 and the locking hook 6 are engaged and the control unit 4 is securely attached to the nose portion 3.
In order to detach the control unit 4 from the equipment body 1, the lock release button 9, formed in the edge portion 3c of the nose portion 3 (see FIG. 7), is depressed. By this action, the locking hook 6 is pivoted clockwise and disengaged from the lock groove 4c. An urging member (not shown) for urging the control unit 4 to detach from equipment body 1 is mounted in the recessed portion 3a of the nose portion 3, and, when the engagement of the locking hook 6 and the lock groove 4c is released, the control unit 4 protrudes while pivoting in a direction .beta. in FIG. 6 under the urging force of the urging member. Then, the projection 3b and the recess 4b are disengaged by the driver/owner while the control unit 4 is held in the driver's hand.
Unfortunately, in the above discussed prior art device, the control unit 4 and the nose portion 3 are completely disengaged on the left side of FIG. 6 when the lock release button 9 (shown in FIG. 7) is depressed. Therefore, unless the control unit 4 is held in the driver's hand, it comes off the nose portion 3 and falls to the floor or ground. Accordingly, the driver must press the lock release button 9 with one hand while holding the control unit 4 in the other hand; this makes handling inconvenient.
Further, in the structure shown in FIGS. 6 and 7, the lock release button 9 is located in the left edge portion 3c (see FIG. 7) of the nose portion 3, to the left of the control unit 4. Therefore, when an attempt is being made to press the lock release button 9, the control unit 4 partially blocks the driver's finger. Furthermore, since the surface area of the edge portion 3c of the nose portion 3 (see FIG. 7) is limited, the lock release button 9 located therein must be relatively small. This is also inefficient.